Data Migration
Migration jobs transfer data from your relational database to MongoDB. Migration jobs use project-level Data Modeling to distribute data to your MongoDB database.
Types of Migration Jobs
Relational Migrator offers two different migration job types:
Snapshot: Snapshot migration jobs run once, typically for a point in time migration strategy.
Continuous: Continuous migration jobs cover new incoming data for a zero-downtime Change Data Capture (CDC) migration strategy. Continuous jobs run a snapshot stage first, followed by a CDC stage that captures database updates in near-real time. The CDC stage updates all new or modified database objects, ignoring any Table Filters set in project-level mapping rules. When you run a continuous migration job, your source and destination database data remain in sync.
Note
Kafka Deployment Model
The Kafka deployment model of Relational Migrator allows you to run longer-running snapshot or continuous migration jobs with improved resiliency. For more details about the Kafka deployment model, see Kafka Deployment Guide.
Recoverability
You can recover a continuous migration job within 24 hours of failure. For details, see Recover a Migration Job.
Compatibility
Some relational databases are only compatible with Snapshot jobs. For more compatibility information, see the following table:
Database | Snapshot Migration Job Support | Continuous Migration Job Support |
|---|---|---|
Databases supported with a JDBC driver |
Some databases might have specific requirements, and Relational Migrator generates a script to modify source databases as necessary. See the following pages to learn more about configuration prerequisites for each type of relational database:
Behavior
Migration jobs are non-idempotent by default. Relational Migrator inserts new documents and embeded arrays each time a job is run, with the option to delete each existing collection at the start of the sync dialogue. You can enable idempotency to delete inserts from the previous migration job automatically.
To enable idempotent inserts for documents and embedded arrays, set
migrator.engine.transform.idempotency: true in the
user.properties file. Enabling idempotency may have substantial
performance impact on large jobs.
Indexes
Relational Migrator creates new indexes in your MongoDB collections to supplement the migration process. For best performance, review the indexes in your collection after migration to ensure that they best fit your application usage patterns.
Relational Migrator does not create new indexes in the relational database. Relational Migrator has read-only access to your source database.
See the following pages for more information on revewing your collection indexes:
Get Started
You can perform the following tasks from the Data Migration tab.
Task | Description |
|---|---|
Create a migration job which uses the defined mapping rules and migration options. | |
View metadata, execution status, and issues for a migration job. | |
Cancels the execution of a migration job. |